v0.12.0

chore: release 0.12.0

Bump forgewire-fabric to 0.12.0. Cumulative changes since 0.11.6: hub routes split into per-domain APIRouter modules, kind:agent runner + live approval roundtrip smoke, ForgeWireAgentRunner NSSM installer + remote wrapper, NSSM start-loop hardening, DELETE /runners/{id} and DELETE /dispatchers/{id} with host_roles dispatch cleanup, smoke harness now self-deregisters. /healthz now exposes package_version as an explicit alias for version. See CHANGELOG.md.